There has been an increasing number of Internet scams designed to trick people into revealing personal information such as credit card numbers, passwords, social security numbers, etc. to unscrupulous individuals who intend to use the information for fraudulent purposes. These scams, also known as “phishing”, usually involve sending electronic messages such as e-mail to unsuspecting users. These messages are designed to appear as though they come from a reputable source, for example e-commerce companies, banks, credit card companies or other well-known people or institutions. The messages are often disguised as security alerts, account maintenance or renewal notices. The messages typically instruct the recipients to enter their personal information in the message, or direct the recipients to a website operated by the fraud message sender where the information may be entered.
Since the messages typically appear to have a legitimate purpose, they often escape the detection of the conventional filtering software used to detect junk electronic messages (commonly referred to as “spam”). In some cases, even when the spam filtering software detects that a message is junk and places it into a spam folder, because the message appears to be authentic, the recipient may reclassify the message and respond to it. It would be desirable to have a technique that would identify the fraudulent messages and prevent users from becoming victims of such scams.